Raymarine C80/Fishfinder

I wonder if anyone has a similar problem & can advise a solution, I have an Oceanis 423 fitted with a Raymarine C80 and the fishfinder intergrated into it, it normally runs for about 30 minutes to about 1 hour, after that time I get a message "No DSM Signal" & the only way to reset it is to switch the power off from the main electrics panel loosing all data from all the instruments. My local Beneteau Agent think it is a power supply problem & are trying to fix it.